John Gill emphasizes that believers should expect to be viewed as strange by the world due to their transformed lives in Christ. He explains that the drastic change in their behavior will lead to misunderstanding and hostility from those who indulge in worldly excesses. Gill encourages the saints not to be discouraged by this opposition, as it stems from the contrast between their righteous living and the sinful practices of others. He highlights the importance of standing firm in faith despite being slandered or criticized for their beliefs and lifestyle.

Ver. 4. Wherein they think it strange,.... Here the apostle points out what the saints must expect from the men of the world, by living a different life; and he chooses to mention it, to prevent discouragements, and that they might not be uneasy and distressed when they observed it; as that they would wonder at the change in their conversations, and look on it as something unusual, new, and unheard of, and treat them as strangers, yea, as enemies, on account of it: that you run not with them into the same excess of riot; to their luxurious entertainments, their Bacchanalian feasts, and that profusion of lasciviousness, luxury, intemperance, and wickedness of all sorts, which, with so much eagerness of mind, and bodily haste, they rushed into; being amazed that they should not have the same taste for these things as before, and as themselves now had; and wondering how it was possible for them to abstain from them, and what that should be that should give them a different cast of mind, and turn of action: speaking evil of you; and so the Syriac and Arabic versions supply "you" as we do; but in the Greek text it is only, "speaking evil of, or blaspheming"; God, Christ, religion, the Gospel, and the truths of it, and all good men; hating them because different from them, and because their lives reprove and condemn them; charging them with incivility, unsociableness, preciseness, and hypocrisy.